The presently disclosed embodiments relate generally to layer(s) that are useful in imaging apparatus members and components, for use in electrostatographic, including digital, apparatuses. More particularly, the embodiments pertain to an improved flexible electrostatographic imaging member utilizing a thermoplastic material pre-compounded to impart conductivity to the formulation of an improved anti-curl back coating layer, and an adhesion promoter may also be included to produce a conductively and optically suitable anti-curl back coating layer of the present disclosure.
Flexible electrostatographic imaging members are well known in the art. Typical flexible electrostatographic imaging members include, for example: (1) electrophotographic imaging member belts (photoreceptors) commonly utilized in electrophotographic (xerographic) processing systems; (2) electroreceptors such as ionographic imaging member belts for electrographic imaging systems; and (3) intermediate toner image transfer members such as an intermediate toner image transferring belt which is used to remove the toner images from a photoreceptor surface and then transfer the very images onto a receiving paper. The flexible electrostatographic imaging members may be seamless or seamed belts; a seamed belt is usually formed by cutting a rectangular imaging member sheet from a web stock, overlapping a pair of opposite ends, and welding the overlapped ends together to form a welded seam belt. Typical electrophotographic imaging member belts include a charge transport layer and a charge generating layer on one side of a supporting substrate layer and an anti-curl back coating coated onto the opposite side of the substrate layer. A typical electrographic imaging member belt does, however, have a more simple material structure; it includes a dielectric imaging layer on one side of a supporting substrate and an ant-curl back coating on the opposite side of the substrate. Although the scope of the present embodiments cover the preparation of all types of flexible electrostatographic imaging members, but for reason of simplicity, the discussion hereinafter will be focused on and represented only by flexible electrophotographic imaging members.
Flexible electrophotographic imaging members do include a photoconductive layer including a single layer or composite layers. Because typical electrophotographic imaging members exhibit undesirable upward imaging member curling, an anti-curl back coating (ACBC) is required to offset the curl. Thus, the application of the anti-curl back coating is necessary to render the imaging member with appropriate flatness.
Electrophotographic imaging members, e.g., photoreceptors, photoconductors, and the like, include a photoconductive layer formed on an electrically conductive substrate. The photoconductive layer is an insulator in the substantial absence of light so that electric charges are retained on its surface. Upon exposure to light, charge is generated by the photoactive pigment, and under applied field charge moves through the photoreceptor and the charge is dissipated.
In electrophotography, also known as xerography, electrophotographic imaging or electrostatographic imaging, the surface of an electrophotographic plate, drum, belt or the like (imaging member or photoreceptor) containing a photoconductive insulating layer on a conductive layer is first uniformly electrostatically charged. The imaging member is then exposed to a pattern of activating electromagnetic radiation, such as light. Charge generated by the photoactive pigment moves under the force of the applied field. The movement of the charge through the photoreceptor selectively dissipates the charge on the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image. This electrostatic latent image may then be developed to form a visible image by depositing oppositely charged particles on the surface of the photoconductive insulating layer. The resulting visible image may then be transferred from the imaging member directly or indirectly (such as by a transfer or other member) to a print substrate, such as transparency or paper. The imaging process may be repeated many times with reusable imaging members.
Multilayered photoreceptors or imaging members have at least two layers, and may include a substrate, a conductive layer, an optional undercoat layer (sometimes referred to as a “charge blocking layer” or “hole blocking layer”), an optional adhesive layer, a photogenerating layer (sometimes referred to as a “charge generation layer,” “charge generating layer,” or “charge generator layer”), a charge transport layer, and an optional overcoating layer in either a flexible belt form or a rigid drum configuration. In the multilayer configuration, the active layers of the photoreceptor are the charge generation layer (CGL) and the charge transport layer (CTL). Enhancement of charge transport across these layers provides better photoreceptor performance. Multilayered flexible photoreceptor members may include an anti-curl back coating layer on the backside of the flexible substrate, opposite to the side of the electrically active layers, to render the desired photoreceptor flatness.
In current organic belt photoreceptors, an anti-curl back coating layer is used to balance residual stresses caused by the top coatings of the photoreceptor and eliminate curling. In addition, the anti-curl back coating layer should have optically suitable transmittance, for example, transparent, so that the photoreceptor can be erased from the back. Existing formulations for anti-curl back coating layers are of low conductivity such that the anti-curl back coating layer takes on a tribo-electrical charge during use in the image-forming apparatus. This tribo-electrical charge increases drag in the image-forming apparatus and increases the load on the motor and wear of the anti-curl back coating layer. The generation of tribo-electrical charge on the anti-curl back coating during electrophotographic imaging processes does at time build-up to the point that stalls the belt cycling altogether. Additional components to resolve or suppress the problem, such as inclusion of active countercharge devices, or additives, such as conductive agents, have been used to attempt to eliminate the tribo-charging of the layer. However, these options are not desirable as they have been found to create other sets of problems. Moreover, they do also increase costs and complexity by including additional components or include additives which produce anti-curl back coating (ACBC) dispersions that do not have the optically suitable clarity.
Thus, there is a need for an improved ACBC that does not suffer from the above-described problems and deficiencies.
Conventional photoreceptors are disclosed in the following patents, a number of which describe the presence of light scattering particles in the undercoat layers: Yu, U.S. Pat. No. 5,660,961; Yu, U.S. Pat. No. 5,215,839; and Katayama et al., U.S. Pat. No. 5,958,638. The term “photoreceptor” or “photoconductor” is generally used interchangeably with the terms “imaging member.” The term “electrostatographic” includes “electrophotographic” and “xerographic.” The terms “charge transport molecule” are generally used interchangeably with the terms “hole transport molecule.”